The K bullet (from German 'Kern', core) was a

7.92×57mm Mauser The 7.92×57mm Mauser (designated as the 8mm Mauser or 8×57mm by the SAAMI and 8 × 57 IS by the C.I.P.) is a rimless bottlenecked rifle cartridge. The 7.92×57mm Mauser cartridge was adopted by the German Empire in 1903–1905, and was the Ge ...

armor-piercing Armour-piercing ammunition (AP) is a type of projectile designed to penetrate either body armour or vehicle armour. From the 1860s to 1950s, a major application of armour-piercing projectiles was to defeat the thick armour carried on many warsh ...

bullet A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. Bullets are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax. Bullets are made in various shapes and co ...

with a

tool steel Tool steel is any of various carbon steels and alloy steels that are particularly well-suited to be made into tools and tooling, including cutting tools, dies, hand tools, knives, and others. Their suitability comes from their distinctive har ...

core designed to be fired from a standard

Mauser Mauser, originally Königlich Württembergische Gewehrfabrik ("Royal Württemberg Rifle Factory"), was a German arms manufacturer. Their line of bolt-action rifles and semi-automatic pistols has been produced since the 1870s for the German arm ...

rifle.

History

The German Army first employed a " reversed bullet" with a heavier powder charge behind it as an early anti-tank method against the

British heavy tanks of World War I British heavy tanks were a series of related armoured fighting vehicles developed by the UK during the First World War. The Mark I was the world's first tank, a tracked, armed, and armoured vehicle, to enter combat. The name "tank" was initial ...

. This did prove effective against the thinner-armored Mark I tank models, mainly by causing

spalling Spall are fragments of a material that are broken off a larger solid body. It can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure (as in a ba ...

from the inside surface of the armor hit. Reversed bullet loads were however unsafe to use in the standard issue Mauser rifle and thus were unpopular with German troops. They became obsolete with the introduction of more heavily armored tanks. As a replacement, the Germans conceived the "K bullet", which was purposely developed as an armor-piercing ammunition. The K bullet was in use by the

battle of Messines Ridge The Battle of Messines (7–14 June 1917) was an attack by the British Second Army (General Sir Herbert Plumer), on the Western Front, near the village of Messines (now Mesen) in West Flanders, Belgium, during the First World War. The Nivel ...

in June 1917 and had one out of three chance to penetrate 12–13 mm thick armor at a range of up to 100 meters. With the British deployment of the

Mark IV tank The Mark IV (pronounced ''Mark four'') was a British tank of the First World War. Introduced in 1917, it benefited from significant developments of the Mark I tank (the intervening designs being small batches used for training). The main impro ...

, which had more armor thickness, the K bullet soon proved ineffective, leading the Germans to design highly specialized anti-tank solutions, with the creation of the powerful 13.2mm TuF cartridge and the first

anti-tank rifle An anti-tank rifle is an anti-materiel rifle designed to penetrate the armor of armored fighting vehicles, most commonly tanks, armored personnel carriers, and infantry fighting vehicles. The term is usually used for weapons that can be carri ...

, the Mauser 1918 T-Gewehr.

Variants

The Germans made several versions of the K bullet during

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

and

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

, including: During the interwar period, Poland produced a copy of S.m.K. bullet designated as P bullet (''przeciwpancerny'') and own armour piercing bullet with a tracer, designated PS (''przeciwpancerny smugowy'').Dąbrowski, Jarosław. ''Amunicja małokalibrowa kampanii wrześniowej'' in: "Strzał" 10/2010, pp. 18-24 (in Polish)

References

{{portal bar, Tanks, World War I Ammunition Anti-tank rounds World War I